NCIDQ IDFX Practice Exam

What scale measures intensity of sound in decibels?

1. Amplitude scale

2. Frequency scale

3. Loudness scale

4. Hertz scale

The correct answer is: Loudness scale

The correct choice, which pertains to how intensity of sound is measured in decibels, is grounded in understanding sound perception and its representation. The loudness scale is indeed utilized to express sound intensity in decibels (dB). This scale reflects the human perception of sound and aligns with how we experience varying volumes. Decibels provide a logarithmic measure of sound pressure levels, which makes it easier to express the wide range of sounds the human ear can detect. Human hearing can perceive intensities spanning from the faintest whisper to the loud sounds of a jet engine, making the decibel scale valuable for quantifying this intensity. In contrast, the amplitude scale relates to the strength of a soundwave's signal but doesn't specifically denote how we perceive that sound in terms of loudness. The frequency scale measures how many cycles per second a sound wave has, representing the pitch rather than loudness. The Hertz scale simply denotes frequency and is not applicable for measuring sound intensity, focusing instead on pitch perception. Thus, the loudness scale stands out as the best choice for measuring sound intensity in decibels, directly corresponding to how we experience and perceive sound in everyday life.